Surgical Cutting Tool

ABSTRACT

Surgical cutting tool for manufacturing of a recess in a firm body tissue, in particular in a bone and/or in a cartilage, with a milling range, which is rotatable around a central axis of rotation, with an outside lateral surface of the milling range and by an internal area, which is substantially defined by the lateral surface and turned away from the worked on body tissue, and the lateral surface is formed with at least two machining cutting edges in terms of a milling head, which proceed at the lateral surface from a machining center to a machining edge of the milling range and which are in particular spiral curved, and apertures are arranged adjacent to the cutting edges for the transport of the cutting splinters into the internal area, whereby the cutting edges are interrupted by means of recesses in such a way that the cutting edges are formed by individually cutting elements.

The invention regards a surgical cutting tool for manufacturing a recess in a firm body tissue, in particular in a bone and/or in a cartilage according to the preamble of one of the claims 1 to 3.

Well-known are surgical cutting tools, as for example described in the EP 1,227,762 B1.

It is disadvantageous that in some cases the produced recesses exhibit a faster and higher erosion in the boundary region than in the central machining center, the so-called pole area.

It is an object of the present invention to provide a surgical cutting tool that makes it possible to work fast and safely and guarantee a pre-determined milling form.

On the one hand the problem is solved by a surgical cutting tool for manufacturing a recess in a firm body tissue, in particular in a bone and/or in a cartilage, with a milling range, which is rotatable around a central axis of rotation, with an outside lateral surface of the milling range and by an internal area, which is substantially defined by the lateral surface and turned away from the treated body tissue, and the lateral surface is formed with at least two machining cutting edges in terms of a milling head, which proceed at the lateral surface from a machining center to a machining edge of the milling range and which are in particular spiral curved, and apertures are arranged adjacent to the cutting edges for the transport of the cutting splinters into the internal area, whereby the cutting edges are interrupted by means of recesses in such a way that the cutting edges are formed by individually cutting elements, and with at least two stopping areas, which are arranged essentially in longitudinal direction in regard to the area and which are arranged essentially parallel and adjacent, and are running at the lateral surface essentially parallel to the cutting edges, and the stopping areas limit the penetration of the cutting edges into the body tissue in relation to the penetration depth into the tissue in a cutting direction transverse to the longitudinal direction of the lateral surface, whereas a first stopping area, which limits a first penetration of the cutting edge into the fabric, has a differential height in relation to the tip of the cutting edge, which originate from the area at the machining center to an area at the machining edge is essentially constant or declining in a small amount and a second stopping area, which limits the penetration following the first penetration of the cutting edge into the tissue, has a height in relation to the tip of the cutting edge, which originating from the area at the machining center to the area at the cutting edge declines.

The stopping areas prevent the cutting edge from penetrating too deeply into the tissue. The cutting edge penetrating into the depth is retarded by the first stopping area. A further retarding is effected by the second stopping area. The height of the stopping areas decreases from the central machining center of the milling head to the edge of the milling head. Thus the attacking strength of the cutting edge is reduced when approaching the edge. The strongest attacking is effected in this way in the machining center and the desired milling form is not falsified.

The problem is solved as well by a surgical cutting tool for manufacturing a recess in a firm body tissue, in particular a bone and/or a cartilage, especially according to claim 1, with a milling range, which is rotatable around a central axis of rotation, with an outside lateral surface of the milling range and by an internal area, which is substantially defined by the lateral surface and turned away from the worked on body tissue, and the lateral surface is formed with at least two machining cutting edges in terms of a milling head, which proceed at the lateral surface from a machining center to a machining edge of the milling range and which are in particular spiral curved, and apertures are arranged adjacent to the cutting edges for the transport of the cutting splinters into the internal area, whereby the cutting edges are interrupted by means of recesses in such a way that the cutting edges are formed by individually cutting elements, with a spiralic narrow channel recess, which is proceeding on the lateral surface, whereas the narrow channel recess breaks through the cutting edges at the lateral surface in the area of the recessions of the cutting edges in such a way, that the narrow channel forms a virtually aligning continuation of the recessions in the cutting edges and a splinter breaking partition of the cutting edges into cutting elements is formed, whereas the length of the cutting elements is declining from the machining center to the machining edge.

The narrow channel recess supports the milling head during the propulsion into the tissue and offers a kind of guidance. At the same time splintered tissue material is delivered up to the next opening by the recess and is transported from there to the inside of the milling head by the opening. At the same time the recesses in the cutting edges have a splinter-breaking effect. The length of the cutting elements formed by the recesses decreases from the machining center to the machining edge. By this a slowing down of the erosion from the machining center to the turning edge is achieved and the forming security during the milling is increased.

The problem is further solved by a surgical cutting tool for manufacturing a recess in a firm body tissue, in particular in a bone and/or in a cartilage, especially according to claim 1 or 2, with a milling range, which is rotatable around a central axis of rotation, with an outside lateral surface of the milling range and by an internal area, which is substantially defined by the lateral surface and turned away from the worked on body tissue, and the lateral surface is formed with at least two machining cutting edges in terms of a milling head, which proceed at the lateral surface from a machining center to a machining edge of the milling range and which are in particular spiral curved, and apertures are arranged adjacent to the cutting edges for the transport of the cutting splinters into the internal area, whereby the cutting edges are interrupted by means of recesses in such a way that the cutting edges are formed by individually cutting elements,

whereas the apertures are formed essentially parallel to the cutting edges and continous open and in the area of the machining center and are ending in the area of the machining edge.

The large openings provide a fast and reliable transport of the splinters. The stability of the milling head is given by the mounting plate at the machining center and at the machining edge.

It is advantageous, if the cutting edges provide, when observed in the cross section, in each case a cutting angle alpha, which is formed between the lateral surface and a cutting surface which is turned away I relation to the workpiece, and which increases from the cutting edge within the area of the machining center to the cutting edge within the area of the machining edge.

It is advantageous, if the cutting edges provide, when observed in the cross section, a relief angle gamma, which is formed between the lateral surface and a cutting surface facing the workpiece, and which decreases from the cutting edge within the area of the machining center to the cutting edge within the area of the machining edge.

It is advantageous, if the relief angle gamma in relation to the distance from the machining center decreases gradually and/or continuously.

It is advantageous, if the stopping areas have a concave cross section.

It is advantageous, if the cutting edge, which is facing the workpiece, is essentially constant over the entire cutting edge.

It is advantageous, if the cross section of the narrow channel recess is expenditure-rounded or angular.

It is advantageous, if the cutting edge is separated by recesses into approximately 5 to 8 cutting elements.

It is advantageous, if the milling range is hemispherical or formed like an triangle or flat or conically or conical or mushroom-shaped

It is advantageous, if the milling range has recesses in the side of the lateral surface, to bring the milling range to difficult accessible areas of the body tissue, whereas the envelope of the milling range remains essentially unchanged compared to a full working tool.

It is advantageous, if the milling range exhibits about 2 to 8, preferably 6, cutting edges which are preferably arranged with a same distance over the lateral surface.

It is advantageous, if the milling range is made of a high-temperature resistant metal especially a CR—CO alloy.

Further characteristics and advantages of the invention result from the claims and the following description, in which examples of the subject of the invention are described in connection with the figures.

FIG. 1 illustrates a cutting tool,

FIG. 2 a illustrates a side view of a cutting tool,

FIG. 2 b illustrates a cutting edge with recesses and cutting elements,

FIG. 3 a illustrates a cross section AA through the lateral surface of FIG. 2 a in the pole area,

FIG. 3 b illustrates a cross section AA through a lateral surface of FIG. 2 a in the equator range,

FIG. 4 illustrates a machining tool in side view,

FIG. 5 a illustrates a machining tool in top view,

FIG. 6 illustrates a machining tool,

FIG. 7 a illustrates a machining tool with side recess and

FIG. 7 b illustrates a machining tool with side recess.

FIG. 1 shows a surgical machining tool with a hemispherical lateral surface 10 and a in this way circumscribed internal area 50 that can be turned around a central axle by means of a bearing shank 40. The turn takes place in this way clockwise if seen from the bearing shank direction. From the machining center, the pole 12, cutting edges extend on cuttings 20, which are separated into separate cutting elements by recesses 30, which penetrate through the cutting edge. The length of the cutting elements decreases from the pole 12 to the equator 14. The cuttings exhibit a cutting surface 28, which is turned away from the workpiece and a cutting surface 26, which is turned to the workpiece.

The recess 30 is built up in form of a spiral over the entire lateral surface from the pole to the equator.

The actual made narrow channel recess, which is built up as a spiral from the pole to the equator, and which can be formed round or square-cut, proceeds through the cutting edges. This forms individual splinter-breaking cutting elements, which are formed by the crossing of the narrow channel with the cutting edges. This causes a better cutting characteristic of the milling means/trephine. Because the overall length of the gumption surface of the cutting edges is reduced by the mechanism of the cutting elements to 70% of the cutting edge length, the danger of getting stuck is substantially reduced. The gumption characteristic is not decreased at the same time and it perfect a cartilage or a bone recess is produced.

The cutting edge is altogether preferably partitioned into about 5 to 8 cutting elements.

The splinter crushers are formed relating to the equator by grooves with a smaller distance to each other. Thus the length of the cutting elements constantly decreases from pole to equator. This again results in the fact that the cutting strength decreases to the equator and the guidance characteristic of the milling tool increases.

Additionally the spiralic groove works as a guiding device, because the cartilage/bone, which is not removed within the splinter crusher range by the cutting element, penetrates into the spiral. This results in a stabilization of the milling tool until the following cutting element removes it. Additionally the groove serves as a feed motion aid, like a corkscrew, as long as pressure is put on the milling cutter.

The milling cutter is held together at the machining center and at the milling edge.

The thickness of the splinters depends upon the difference between the cutting edge and the adjacent lateral surface, whereby the opening between lateral surface and cutting edge is arranged for conducting of the cutting splinters. The working height between the tip of the cutting edge and the end of the second lateral surface (10 b) decreases preferably continuously from the cutting edge range in the machining center (h1 b) to the cutting edge range in the milling edge (h2 b). This strongly increases the guidance characteristic.

The lateral surface of the milling tool is formed between two cutting edges respectively of two different surfaces, a first one, which is formed turned away of the cutting edge and a second surface, which extends to the opening between this and the adjacent cutting edge. The surfaces serve as feed stoppers. By a differently increasing distance in relation to the absolute milling form the surfaces provide a higher intensity for the milling tool.

The difference between the second surface and the surface of the following cutting edge by a decreasing distance to the equator leads to more strength in the pole area and thus to a better guiding to a certain direction.

The cutting edge surface has the same width on the entire length from pole to equator.

The openings in the lateral surfaces, which are in front of each cutting edge, extend from a distance from approximately 5 to 7 mm relative to the machining center (“pole”) up to a distance of approximately 3 mm relative to the milling edge (“equator”).

By the invention a recess is formed in a hard body tissue, especially bones or a cartilage.

This recess can be in particular hemispherical and can serve as an intrusion area for example for a hip joint protheses. 

1. Surgical cutting tool for manufacturing of a recess in a firm body tissue, in particular in a bone and/or in a cartilage, with a milling range, which is rotatable around a central axis of rotation, with an outside lateral surface of the milling range and by an internal area, which is substantially defined by the lateral surface and turned away from the worked on body tissue, and the lateral surface is formed with at least two machining cutting edges in terms of a milling head, which proceed at the lateral surface from a machining center to a machining edge of the milling range and which are in particular spiral curved, and apertures are arranged adjacent to the cutting edges for the transport of the cutting splinters into the internal area, whereby the cutting edges are interrupted by means of recesses in such a way that the cutting edges are formed by individually cutting elements, and with at least two stopping areas, which are arranged essentially in longitudinal direction in regard to the area and which are arranged essentially parallel and adjacent, and are running at the lateral surface essentially parallel to the cutting edges, and the stopping areas limit the penetration of the cutting edges into the body tissue in relation to the penetration depth into the tissue in a cutting direction transverse to the longitudinal direction of the lateral surface, whereas a first stopping area, which limits a first penetration of the cutting edge into the fabric, has a differential height in relation to the tip of the cutting edge, which originate from the area at the machining center to an area at the machining edge is essentially constant or declining in a small amount and a second stopping area, which limits the penetration following the first penetration of the cutting edge into the tissue, has a height in relation to the tip of the cutting edge, which originating from the area at the machining center to the area at the cutting edge declines.
 2. Surgical cutting tool for manufacturing a recess in a firm body tissue, in particular in a bone and/or in a cartilage, especially according to claim 1, with a milling range, which is rotatable around a central axis of rotation, with an outside lateral surface of the milling range and by an internal area, which is substantially defined by the lateral surface and turned away from the worked on body tissue, and the lateral surface is formed with at least two machining cutting edges in terms of a milling head, which proceed at the lateral surface from a machining center to a machining edge of the milling range and which are in particular spiral curved, and apertures are arranged adjacent to the cutting edges for the transport of the cutting splinters into the internal area, whereby the cutting edges are interrupted by means of recesses in such a way that the cutting edges are formed by individually cutting elements, with a spiralic narrow channel recess, which is proceeding on the lateral surface, whereas the narrow channel recess breaks through the cutting edges at the lateral surface in the area of the recessions of the cutting edges in such a way, that the narrow channel forms a virtually aligning continuation of the recessions in the cutting edges and a splinter breaking partition of the cutting edges into cutting elements is formed, whereas the length of the cutting elements is declining from the machining center to the machining edge.
 3. Surgical cutting tool for manufacturing a recess in a firm body tissue, in particular in a bone and/or in a cartilage, especially according to claim 1, with a milling range, which is rotatable around a central axis of rotation, with an outside lateral surface of the milling range and by an internal area, which is substantially defined by the lateral surface and turned away from the worked on body tissue, and the lateral surface is formed with at least two machining cutting edges in terms of a milling head, which proceed at the lateral surface from a machining center to a machining edge of the milling range and which are in particular spiral curved, and apertures are arranged adjacent to the cutting edges for the transport of the cutting splinters into the internal area, whereby the cutting edges are interrupted by means of recesses in such a way that the cutting edges are formed by individually cutting elements, whereas the apertures are formed essentially parallel to the cutting edges and continuously open and in the area of the machining center and are ending in the area of the machining edge.
 4. Surgical cutting tool according to claim 1, wherein the cutting edges provide, when observed in the cross section, a cutting angle alpha respectively, which is formed between the lateral surface and a cutting surface (28) which is turned away I relation to the workpiece, and which increases from the cutting edge within the area of the machining center to the cutting edge within the area of the machining edge.
 5. Surgical cutting tool according to claim 1, wherein the cutting edges provide, when observed in the cross section, a relief angle gamma, which is formed between the lateral surface and a cutting surface facing the workpiece, and which decreases from the cutting edge within the area of the machining center to the cutting edge within the area of the machining edge.
 6. Surgical cutting tool according to claim 1, wherein the relief angle gamma in relation to the distance from the machining center decreases gradually and/or continuously.
 7. Surgical cutting tool according to claim 1, wherein the stopping areas have a concave cross section.
 8. Surgical cutting tool according to claim 1, wherein the cutting edge (26), which is facing the workpiece, is essentially constant over the entire cutting edge.
 9. Surgical cutting tool according to claim 1, wherein the cross section of the narrow channel recess is expenditure-rounded or angular.
 10. Surgical cutting tool according to claim 1, wherein the cutting edge is separated by recesses into approximately 5 to 8 cutting elements.
 11. Surgical cutting tool according to claim 1, wherein the milling range is hemispherical or formed like an triangle or flat or conically or conical or mushroom-shaped.
 12. Surgical cutting tool according to claim 1, wherein the milling range has recesses in the side of the lateral surface, to bring the milling range to difficult accessible areas of the body tissue, whereas the envelope of the milling range remains essentially unchanged compared to a full working tool.
 13. Surgical cutting tool according to claim 1, wherein the milling range exhibits about 2 to 8, preferably 6, cutting edges which are preferably arranged with a same distance over the lateral surface.
 14. Surgical cutting tool according to claim 1, wherein the milling range is made of a high-temperature resistant metal especially a CR—CO alloy. 